RRC 5G UE -> gNB 3GPP TS 38.331

5G NR - Measurement Report

Measurement Report is the NR RRC message a UE sends to the gNB when configured measurement conditions are met, allowing the network to make mobility, beam, and radio-resource decisions.

Message Fact Sheet

Protocol	rrc	Network	5g
Spec	3GPP TS 38.331	Spec Section	5.5, 6.3.2
Direction	UE -> gNB	Message Type	Mobility / Measurement

Full message name	5G NR - Measurement Report
Protocol	RRC
Technology	5G
Direction	UE -> gNB
Interface	Uu
Signaling bearer / channel	SRB1 / DCCH
Typical trigger	Sent when an event-based or periodic measurement configuration condition is satisfied, such as A3, A5, beam, or report-quantity criteria.
Main purpose	Carries measured radio results for serving and neighbor cells so the gNB can trigger handover, reconfiguration, beam management, or other mobility-related actions.
Main specification	3GPP TS 38.331, 5.5, 6.3.2
Release added	Release 15
Procedures where used	5G Measurement Reporting, Connected-Mode Mobility, Handover Preparation, Beam Management
Related timers	Measurement reporting behavior depends on report configuration, event conditions, hysteresis, time-to-trigger, and measurement gaps, Engineers usually correlate reporting timing with configured measurement IDs rather than a single transaction timer inside Measurement Report
Related cause values	Measurement Report does not carry reject causes, Problems are usually inferred from missing reports, stale results, wrong event triggering, or inconsistent mobility action after reporting

What is Measurement Report in simple terms?

Measurement Report is the NR RRC message a UE sends to the gNB when configured measurement conditions are met, allowing the network to make mobility, beam, and radio-resource decisions.

Carries measured radio results for serving and neighbor cells so the gNB can trigger handover, reconfiguration, beam management, or other mobility-related actions.

Why this message matters

Measurement Report is the 5G NR message the UE sends to tell the network what radio conditions it is seeing so the network can make mobility decisions.

Where this message appears in the call flow

Measurement Reporting

Call flow position: Sent after the UE has been configured with measurement objects, report configurations, and measurement identities.

Typical state: UE is in connected mode and actively evaluating reporting conditions.

Preconditions:

The UE has valid measurement configuration.
The UE is in a state where reporting is allowed.
The configured event or periodic condition has been satisfied.

Next likely message: RRC Reconfiguration, handover-related signaling, or no immediate action depending on network policy

Connected-Mode Mobility

Call flow position: Used when the gNB needs fresh measurement results before deciding on handover or mobility optimization.

Typical state: UE is connected and radio conditions are being tracked.

Preconditions:

Serving-cell and neighbor-cell measurements are being collected.
A mobility-relevant condition exists, such as degrading serving quality or improving neighbor quality.

Next likely message: Handover-related RRC action or updated measurement configuration

Beam Management / Radio Optimization

Call flow position: Relevant when measurement reporting is used for beam quality decisions or radio tuning.

Typical state: UE is connected and measurements are being used for optimization rather than immediate handover.

Preconditions:

Relevant beam or cell measurement configuration is active.

Next likely message: Updated configuration or continued monitoring

Call flow position

Previous message(s): RRC Reconfiguration, Measurement configuration delivery

Next message(s): RRC Reconfiguration, Handover command or mobility action, Beam or measurement-related network optimization decision

Message direction and transport

Sender and receiver: UE -> gNB

Interface: Uu

Domain: Access-side radio control and mobility optimization

Signaling bearer: SRB1

Logical channel: DCCH

Transport / encapsulation: Dedicated RRC signaling on DCCH after measurement configuration has been delivered to the UE

Security context: Dedicated UE-specific AS-protected RRC signaling after security activation in connected mode.

Message Structure Overview

Measurement Report is a compact dedicated message whose real meaning comes from the measurement configuration that existed before it.
For engineering work, the most important question is not only what values are present, but which measurement identity triggered the report and why.
The message is usually interpreted together with the earlier RRC Reconfiguration that created the measurement objects and reporting rules.

ASN.1 for 5G NR - Measurement Report

UL-DCCH-Message ::= SEQUENCE {
  message CHOICE {
    c1 CHOICE {
      measurementReport MeasurementReport,
      ...
    },
    ...
  }
}

MeasurementReport ::= SEQUENCE {
  criticalExtensions CHOICE {
    measurementReport MeasurementReport-IEs,
    ...
  }
}

MeasurementReport-IEs ::= SEQUENCE {
  measResults MeasResults,
  ...
}

How to read this ASN.1

The ASN.1 is simple at the top level. In practice, the heavy lifting is inside MeasResults and the linked measurement configuration, especially measId, reportConfig, and the measurement object that caused the report.

Decoded Message Dump

UL-DCCH-Message
  message: c1
    measurementReport
      criticalExtensions
        measurementReport
          measResults
            measId: 3
            measResultServingMOList
              [0]
                pci: 101
                rsrp: -92 dBm
                rsrq: -11 dB
            measResultNeighCells
              measResultListNR
                [0]
                  pci: 205
                  rsrp: -84 dBm
                  rsrq: -9 dB

How to read this dump

measId is usually the first field to inspect because it tells you which configured reporting rule triggered the message.
The serving and neighbor result values should be interpreted against the configured event logic, not in isolation.
A stronger neighbor alone does not guarantee handover; it only shows that the UE reported what the configured rule asked for.

Important Information Elements

IE	Required	Description
`measResults`	Yes	The core payload containing serving-cell and neighbor-cell measurement results.
`measId`	Yes	Identifies which measurement configuration triggered the report.
`rsrp / rsrq / sinr related values`	Optional	Operationally important radio metrics used to understand why the report was triggered.
`neighbor cell result set`	Optional	Shows which candidate cells or beams are being considered by the network.

Detailed field explanation

`measResults`

The core payload containing serving-cell and neighbor-cell measurement results.

Presence: Required

In practice: In practice, compare this field with the original request and with any later release-dependent optional fields so you can see whether the network accepted the same service model the UE asked for.

`measId`

Identifies which measurement configuration triggered the report.

Presence: Required

`rsrp / rsrq / sinr related values`

Operationally important radio metrics used to understand why the report was triggered.

Presence: Optional

`neighbor cell result set`

Shows which candidate cells or beams are being considered by the network.

Presence: Optional

What to check in logs and traces

Check which RRC Reconfiguration delivered the relevant measurement object, report configuration, and measId.
Verify that the reported measId matches the event or periodic rule you expect.
Inspect serving and neighbor values together, especially around A3 or threshold-based triggers.
If no report appears, check event conditions, hysteresis, time-to-trigger, measurement gaps, and radio stability.
Correlate the report with the next network action, such as handover, reconfiguration, or no action.
Separate a missing report problem from a correct report followed by an unexpected mobility decision.

Common Issues and Troubleshooting

The network expected a handover report, but no Measurement Report was sent.

Likely cause: The event criteria may not have been met, the configuration may be wrong, or measurement gaps may be missing.

What to inspect: Check measId setup, event thresholds, time-to-trigger, hysteresis, and whether the neighbor was actually measurable.

Next step: Compare the live radio values with the configured trigger logic before assuming UE failure.

Measurement Report is sent, but handover does not happen.

Likely cause: The report may be correct, but the network decision policy may not select handover.

What to inspect: Check the reported values, load context, mobility restrictions, and the following RRC or handover decision.

Next step: Treat this as a mobility-decision issue, not automatically a Measurement Report issue.

Reports appear too often or look unstable.

Likely cause: The reporting configuration may be too sensitive, or radio conditions may be fluctuating.

What to inspect: Check hysteresis, time-to-trigger, report intervals, and the stability of serving and neighbor measurements.

Next step: Tune the measurement configuration or investigate the radio environment.

LTE / 5G / Variant Comparison

Measurement Report versus RRC Reconfiguration

RRC Reconfiguration tells the UE what to measure and when to report. Measurement Report is the UE's actual feedback after those conditions are met.

Measurement Report versus handover signaling

Measurement Report informs the network. It does not itself command handover. The later mobility action is a separate network decision.

FAQ

What is Measurement Report in 5G NR?

Measurement Report is the NR RRC message a UE sends when configured radio measurement conditions are satisfied.

Who sends the 5G Measurement Report?

The UE sends Measurement Report to the gNB over dedicated RRC signaling.

What comes before Measurement Report?

Usually an RRC Reconfiguration that sets up the measurement objects, report configuration, and measurement identity.

What comes after Measurement Report?

That depends on network policy. It may be followed by handover-related signaling, an updated reconfiguration, or no immediate action.

Why is measId important in Measurement Report?

Because it tells engineers which configured reporting rule triggered the report.

Does Measurement Report mean handover will happen?

No. It only provides radio information. Handover is a later network decision.

Related message pages

Related Procedures

Related Tools

Use This Reference in Practice

Decode this message with the 3GPP Decoder, inspect the related message database, or open the matching call flow to see where this signaling step fits in the full procedure.